British Standard 4043:1966 entitled "Recommendations for transplanting semi-mature trees", and Civic Trust (UK) publication "Practice notes on the transplanting of semi-mature trees" refer to the subject in recent years.
This inventor's British Pat. Nos. 992,491 and 1,094,890 introduced mechanical aids to wrapping and transplanting during 1962-1966. Other patents based on U.K. Patent No. 992,491 were U.S. Pat. No. 3,190,465; West German Pat. No. 1,175,933; French Pat. No. 1,325,813; Italian Pat. No. 665,173 and Canadian Pat. No. 693,367. U.S. Pat. No. 2,990,630 of 1961 referred to the design of a tree moving machine manufactured by Vermeer Mfg. Co. Pella, Iowa, USA, and later superseded by the range of Vermeer "Tree Spades" designated TS 30, TS 44, TS 66 for which there was no patent protection specified in the sales literature.
Within the past five years variants of the Tree Spade concept have been marketed from the USA by Spartan Landscaping, Lancing 48833, Mich., under the name "Big John" and in West Germany under the name "Optimal" by Opitz GmbH & Co KG, 8548 Heideck/Seiboldsmuhle. These variants of the "Tree Spade" concept differ mainly by the use of double curvature blades forced into the soil along a curved path in place of straight section blades. All such machines of the "Tree Spade" concept employ a multiplicity of blades, usually four, guided by a rigid frame having a hinged gate to permit the positioning of the apparatus about the tree. Each blade is forced into the ground by a hydraulic ram that reacts against the mass of the apparatus. The said mass coupled with the anchorage achieved by part driven blades limits the rate and extent of penetration by any one blade, until in the end position the driven blades substantially enclose a ball of soil containing part of the tree's roots. These previous designs are each mounted on a vehicle ranging from farm tractors up to eight wheel trucks for the larger versions transplanting a tree with soil-ball approximately 2 m diameter. The whole apparatus normally travels with one tree thus loaded for transplanting. The smaller versions may disgorge the soil-ball above ground level for wrapping by hand or with a pre-formed container to achieve greater economy of transport and output. Because of each machine's considerable mass and size when mounted on its integral vehicle it is unsuitable in practice for digging a soil ball substantially less than its designed maximum soil ball. This deficiency is reinforced by the economic constraints of growing trees in plantations and nurseries at the closest spacing compatible with available transplanting techniques.